The use of hematoporphyrin derivative and other photosensitizing agents in combination with light activation is currently being investigated as an anti-tumor modality for the treatment of intraperitoneal and intrathoracic tumors. A major advantage of this modality is the apparent selective retention of the sensitizing dye with tumors. Initially, murine models were used to study the tolerance of the thoracic cavity structures to the phototherapy techniques being explored. The limitations of the murine model has required the extensions of the investigation to the canine model for evaluation of the toxicity of Phototherapy. Different wavelengths of light, different laser delivery systems, different sensitizers, different doses of energy, different modes of drug administration, and different monitoring devices were studied. We have extended a toxicity study to the canine thoracic cavity and shown that structures such as the esophagus, parietal and visceral pleura, heart can tolerate 35 J.cm2 red light. An athymic murine model transplanted with human lung cancer was used to study photoimmunotherapy. Hematoporphyrin was covalently bound to the specific monoclonal antibody directed against the xenograft. The results show that tumor can be eradicated and that dermatophototoxicity is eliminated. We have had interest in confirming work by others to determine if ultrasonic activation of Hp in murine systems is a reasonable area of research effort.